Couplings are for example known comprising a male element and a female element as stated, plus an elastically deformable element which embraces the female element, said elastically deformable element being itself embraced by an axially slidable release collar. In such couplings, the female element also comprises two diametrically opposing identical apertures through which two locking teeth associated with said elastically deformable element are permanently inserted. In the known prior art, this latter element comprises two opposing semicircular members provided with said two teeth which project inwards, the facing ends of said semicircular members being connected together by two thin open-ring sections which are bent at an angle back upon themselves along a middle axis so that their concavities face towards the outside of the coupling.
An elastically deformable element of the aforesaid type is described in Italian patent application No. 23847 A/80, which corresponds to U.S. Pat. No. 4,429,906, to which reference should be made for further details.
With the structure described in said document, when the elastically deformable element is made to embrace the female element, the two teeth are elastically urged towards the longitudinal axis of the coupling, and partially penetrate into the female element, said open-ring sections, which act as springs, keeping the collar elastically urged into its locking position, by way of the semicircular members from which the teeth branch. As the male element is inserted into the female element, which is done without sliding the column, the two teeth are forced outwards by said male element until they make contact with the inner surface of the collar, to then rotate about their point of contact with this latter, and finally project towards the inside of the female element when they become aligned with an engagement groove provided in the male element.
When the male element is to be removed, the collar is moved against the thrust of the elastic element, so that said collar engages with said semicircular members and also drags the teeth, which make contact with the inclined lower edge of the apertures provided in the female element. Because of said inclined or sliding edge, the teeth withdraw from said apertures until the male element is completely freed and can therefore be withdrawn, the collar on being released automatically returning to its locking position.
The use of the aforesaid known couplings has shown that they have a tendency to wear with a certain rapidity in the zones in which the major sliding action occurs, in particular at the surfaces of the teeth and apertures which undergo the said contact during the release of the male element.
With the continual repetition of the release operations, the degree of wear of said surfaces increases correspondingly, and consequently the release becomes particularly difficult and uncomfortable to effect, with the final danger of irreversible engagement.